1. Field of the Invention
The present invention relates to a reciprocating compressor, and, more specifically, to a reciprocating compressor with an improved structure of a suction chamber suitable for use in a refrigerating cycle of an air conditioner for vehicles.
2. Description of the Prior Art
Generally, in a reciprocating compressor, a gas is introduced from a suction chamber into a reciprocating mechanism having a plurality of bores and a plurality of pistons. The compressed gas by the reciprocating mechanism is introduced into a discharge chamber and then discharged therefrom. The suction chamber and the discharge chamber usually are formed in a cylinder head.
For example, as depicted in FIG. 4, discharge chamber 101 is formed at a radially central portion of cylinder head 102. Suction chamber 103 is formed around discharge chamber 101 to extend in the circumferential direction of discharge chamber 101 at a radially outer portion of discharge chamber 101. Partition wall 104 separates suction chamber 103 from discharge chamber 101. Outer wall 105 defines suction chamber 103. A gas is introduced into suction chamber 103 through suction port 106. The gas is displaced from suction chamber 103 into bores 107 in a cylinder block (not shown). The compressed gas within each bore 107 is displaced into discharge chamber 101, and then discharged from discharge chamber 101 through discharge port 108.
Partition wall 104 has a plurality of concave surfaces 104a and a plurality of convex surfaces 104b on its radially outer surface. Concave surfaces 104a and convex surfaces 104b are arranged alternately to form a continuous convex/concave curved surface. Outer wall 105 has a plurality of portions 109 projecting toward the respective concave surfaces 104a of partition wall 104 on its radially inner surface 105a. Projecting portions 109 are arranged at a predetermined interval in the circumferential direction of outer wall 105. A screw hole 110 is defined in each projecting portion 109. Other than projecting portions 109, the thickness of outer wall 105 is substantially constant.
In a known compressor, suction flow conditions of the gas in bores 107 tend to become nonuniform because suction chamber 103 extends in the circumferential direction and the gas is introduced into suction chamber 103 through suction port 106, which is typically a single port. This condition may cause a decrease of refrigeration ability due to the reduction of the volume efficiency of the suction gas and the occurrence of vibration and noise due to pulsating suction. In particular, as depicted in FIG. 4, two gaps, which have differing widths L1 and L2, are formed in suction chamber 103. Width L1 is formed between the inner surface 105a of outer wall 105 and the convex surface 104b of partition wall 104. Width L1 is greater than width L2, which is formed between the inner surface of projecting portion 109 of outer wall 105 and the convex surface 104b of partition wall 104. Therefore, a gap having width L2 acts as a throttle against the gas flow in suction chamber 103. Consequently, as depicted by arrow A in FIG. 4, a break away flow A may be generated with the gas flow in suction chamber 103 at a position immediate downstream of the gap portion having width L2 in the direction of the gas flow, or at a position of the downstream side of projecting portion 109. Such a break away flow A may increase the pressure loss in the gas flow, may decrease suction efficiency into each bore 107. Further, the volume of the gas sucked into the respective bores 107 may become nonuniform. As a result, in a refrigeration system, the refrigeration ability may decrease. Moreover, break away flow A may cause a pulsation of suction, and it may increase vibration and noise within the compressor.
Japanese Utility Model Laid-Open 61-145884 or JP-A-7-139463 discloses a structure wherein a suction chamber, or a suction path, is formed so as to cross a discharge chamber at a central portion over the discharge chamber, or a structure wherein the height of a narrow portion of a suction chamber is enlarged by heightening a partition wall between the discharge chamber and the suction chamber. However, if a suction chamber is formed to cross over a discharge chamber, then it may be necessary to reduce the height of a discharge chamber in the axial direction of the compressor, or to enlarge the height of the suction chamber. If the narrow portion of the suction chamber is enlarged in the axial direction of the compressor, then the axial length of the entire compressor may increase, and may cause a deterioration of workability for mounting the compressor on a vehicle. Further, in both structures, the weight of a compressor may increase accompanying with the increase of the axial length.